deemph.c revision 13158e7c748c760d238fd5e965805d251fcf2776 
1/*
2 ** Copyright 2003-2010, VisualOn, Inc.
3 **
4 ** Licensed under the Apache License, Version 2.0 (the "License");
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
8 **     http://www.apache.org/licenses/LICENSE-2.0
9 **
10 ** Unless required by applicable law or agreed to in writing, software
11 ** distributed under the License is distributed on an "AS IS" BASIS,
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16
17/***********************************************************************
18*       File: deemph.c                                                 *
19*                                                                      *
20*	   Description:filtering through 1/(1-mu z^ -1)                    *
21*	               Deemph2 --> signal is divided by 2                  *
22*				   Deemph_32 --> for 32 bits signal.                   *
23*                                                                      *
24************************************************************************/
25
26#include "typedef.h"
27#include "basic_op.h"
28#include "math_op.h"
29
30void Deemph(
31		Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
32		Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
33		Word16 L,                             /* (i)     : vector size                            */
34		Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
35	   )
36{
37	Word32 i;
38	Word32 L_tmp;
39
40	L_tmp = L_deposit_h(x[0]);
41	L_tmp = L_mac(L_tmp, *mem, mu);
42	x[0] = vo_round(L_tmp);
43
44	for (i = 1; i < L; i++)
45	{
46		L_tmp = L_deposit_h(x[i]);
47		L_tmp = L_mac(L_tmp, x[i - 1], mu);
48		x[i] = voround(L_tmp);
49	}
50
51	*mem = x[L - 1];
52
53	return;
54}
55
56
57void Deemph2(
58		Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
59		Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
60		Word16 L,                             /* (i)     : vector size                            */
61		Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
62	    )
63{
64	Word32 i;
65	Word32 L_tmp;
66	L_tmp = x[0] << 15;
67	L_tmp += ((*mem) * mu)<<1;
68	x[0] = (L_tmp + 0x8000)>>16;
69	for (i = 1; i < L; i++)
70	{
71		Word32 tmp;
72		L_tmp = x[i] << 15;
73		tmp = (x[i - 1] * mu)<<1;
74		if (tmp > 0 && L_tmp > INT_MAX - tmp) {
75			L_tmp = INT_MAX;
76		} else if (tmp < 0 && L_tmp < INT_MIN - tmp) {
77			L_tmp = INT_MIN;
78		} else {
79			L_tmp += tmp;
80		}
81		if (L_tmp > INT32_MAX - 0x8000) {
82			L_tmp = INT_MAX - 0x8000;
83		}
84		x[i] = (L_tmp + 0x8000)>>16;
85	}
86	*mem = x[L - 1];
87	return;
88}
89
90
91void Deemph_32(
92		Word16 x_hi[],                        /* (i)     : input signal (bit31..16) */
93		Word16 x_lo[],                        /* (i)     : input signal (bit15..4)  */
94		Word16 y[],                           /* (o)     : output signal (x16)      */
95		Word16 mu,                            /* (i) Q15 : deemphasis factor        */
96		Word16 L,                             /* (i)     : vector size              */
97		Word16 * mem                          /* (i/o)   : memory (y[-1])           */
98	      )
99{
100	Word16 fac;
101	Word32 i, L_tmp;
102
103	fac = mu >> 1;                                /* Q15 --> Q14 */
104
105	L_tmp = L_deposit_h(x_hi[0]);
106	L_tmp += (x_lo[0] * 8)<<1;
107	L_tmp = (L_tmp << 3);
108	L_tmp += ((*mem) * fac)<<1;
109	L_tmp = (L_tmp << 1);
110	y[0] = (L_tmp + 0x8000)>>16;
111
112	for (i = 1; i < L; i++)
113	{
114		L_tmp = L_deposit_h(x_hi[i]);
115		L_tmp += (x_lo[i] * 8)<<1;
116		L_tmp = (L_tmp << 3);
117		L_tmp += (y[i - 1] * fac)<<1;
118		L_tmp = (L_tmp << 1);
119		y[i] = (L_tmp + 0x8000)>>16;
120	}
121
122	*mem = y[L - 1];
123
124	return;
125}
126
127
128
129